Vulcanization accelerators



Patented July 19, 1949 imirso ,S-TATss PATENT oFFicE "signal-to Unit'ed""-States Rubber CompanyjNw York, N. ahorpdration of New Jersey No granting. Application December 18, E341}, T seminar/Pansy 4 Claims. (01. egg-t gers) 1 This invention relates to a new class of chemicals valuable as accelerators for the vulcanization of rubber or other vmgaii a b g rubbe'r'j lilr'e substances.

An object of the invention is to provide a new class of accelerators for the vulcanization of natural or synthetic rubber. Another object is to provide accelerators having thermal stability and storage stability, and providing safety from score in rubber. Q'ther objectswillbe apparent from the hereinafter description; y

' The new'acdelerators "s'ubscribe'to the formula y H Ar %CSNT where Ar is an orthmarylene nucleus, and T represents a thiolanyl group H2 l/ 4 Ci the dangling short valences of which are satisneed by hy rogen,andnyar arn cor p ing to the appropriate 'diene hydrocarbon from which the thionhyrgrbupis' derived by reaction with sulfur dioxide. The chemicals are generally termed benzothiazole N-1,1-dioxo 3-thiolanyl sulfenamides, of which the most prominent and preferred member is benzothiazole N-1,1-dioxo B-thiolanyl sulfenamide, considered to have the formula The selected diene is first condensed with sulfur dioxide to form the corresponding 1,1-di0xo thiolene-3. This is illustrated for butadiene-1,3 and sulfur dioxide by the equation OH 4 \C 2 (1,1-dioxo-thiolene-3 or butadiene sulfone).

In place of butadiene-1,3, there may be used substituted-butadienes-1,3 such as isoprene, pi-

am he iker are the 9 Q N lil-qi heels N ide (der-i The following examples, in which the parts are by weight, further illustrate the invention: 1

Example 1.Preparation Z-benzothiazole sulfenamide (10 g.0.55 mol) is mixed with 30 g. 1,1-dioxo 3-amino thiolane and the mixture warmed 5 hours at 40-50 C. Ammonia is freely evolved at first, but during the last half hour of reaction, little or no ammonia is observed. A very viscous oil resulted, in which there is some suspended matter. On adding a mixture of water and ordinary ether, a solid separates which is filtered, Washed and recrystallized from 50 cc. boiling alcohol (ethanol). A yield of 9.5 g. pure benzothiazole N-1,1-dioxo 3- thiolanyl sulfenamide melting 113-115 C. is obtained.

. Theory for Analysis Found cuHnozNzsa Nitrogen 7. 82 9. 3 Sulfur 32.9 32.0

Example 2.-Acceleratz'cn Tests A rubber compound of the following recipe is cured and tensiled in the usual manner:

Butadiene-styrene copolymer rubber Cured 45 and 60 minutes at 45 pounds per square inch steam pressure; T is tensile in pounds per square inch and E is elongation:

Cure 'l E 45145 700 300 1,820 500 2,700 670 (Break) 60145 1, 100 300 v 2,600 500 2, 900 515 (Break) Scorch Tests Scorch tests were run at pounds per square inch steam for 60, 120, 150 and 240 minutes:

Cure '1 E The accelerators may be used to accelerate the vulcanization of any of the natural or synthetic rubbers which ordinarily lend themselves to cure with sulfur or other curing agent susceptible to acceleration, and which includes the Buna. type rubbers (rubbery polymers essentially derived from butadiene-1,3) such as GRS (rubbery copolymer of butadiene-1,3 and styrene), GRA (rubbery copolymer of butadiene-1,3 and acrylonitrile), GRM (polychloroprene), polyisoprene, poly-butadiene-1,3, etc., and latices of such rubbers and the rubbers laid down from such latices. The present accelerators may be used in the same proportion in the rubber, as is used with other conventional accelerators in the vulcanization of the various rubbers. They also may be used alone or in conjunction with conventional accelerator activators such as diphenyl guanidine, etc., or with such as mercapto-benzothiazole.

Other ratios of the compounding ingredients than those given in Example 2, as well as other desired fillers, pigments, softeners, antioxidants, and the like, may be employed in the production of various types of rubber compounds, as will be apparent to those skilled in the art of vulcanization of rubber.

While I have shown and described various embodiments of the invention, it is to be understood that the invention is susceptible to other modifications which appear within the spirit of the invention and the scope of the appended claims. Having thus described my invention, what I claim and desire to protect by Letters Patent 15:

1. A compound of the formula N Ar where Ar is an ortho-arylene nucleus and T is a 1,1-dioxo 3-thlolanyl group.

2. A compound of the formula where Ar is an ortho-benzene nucleus and T is a 1,1-dioxo s-thiolanyl group.

3. A benzothlazole N-Ll-dioxo 3-thiolanyl sulfenamide.

4. Benzothiazole N-l,l-dioxo 3-thiolanyl sulfenamide.

LYNDON B. TEWKSBURY, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,219,006 Delfs Oct. 22, 1940 2,231,353 Watt Feb. 11, 1941 2,273,323 Jones Feb. 17, 1942 2,382,793 Howland Aug. 14, 1945 

